Pelletized feeds have long been known and are recognized as serving useful purposes in the field of animal nutrition. Such pelletized feeds have been produced by a variety of methods and from a variety of ingredients. An important additive to feeds to be pelletized has been fat.
Many years ago, fat was added to the feed mixture prior to the pelletizing operation and the mixture was then heated and forced through the die of a pellet mill. However, this method was very crude and had several drawbacks such as, the amount of added fat was limited to less than 4 percent and the pellet was of extremely poor structural quality. Specifically, the resultant pellets were soft and disintegrated readily into meal with the amount of fines ranging up to 45-50 percent. Such soft pellets were not of marketable quality.
Later, attempts were made to produce these pellets from a feed mixture having as much as 10 percent fat, but an undesirable soft product with a greasy surface resulted. Under normal warehouse storage conditions these pellets were completely deformed to a pulpy mass.
More recently, other processes such as described in U.S. Pat. No. 3,014,800 and U.S. Pat. No. 2,945,764 have attempted to solve the above-described problems related to manufacturing high fat pellets by a more expensive and time consuming technique of first mixing and comminuting a composite of ingredients, then the ingredients are pelleted, afterwards the pellets are dried and finally hot liquid fat is sparyed onto the hot pellets. Although this method provides hard pellets, the maximum amount of total fat which can be incorporated within and onto the pellet without causing undesirable crumbling and a high percentage of fines is from 10-20 percent.
It is also noted that the prior art methods utilized oleaginous seed meal as a feed ingredient which was defatted or had its natural oil removed. Accordingly, it was thought imperitive that in order to adequately obtain a fat content approaching 20 percent, the fat or oil would have to be added to the pellets in a separate step subsequent to pelletizing, otherwise the degradation of particle hardness would result. Additionally, it was thought that obtaining a fat content which exceeded 20 percent would be impossible without softness, friability, crumbling and greasy texture.
However, it is now desirable that animals such as horses, poultry, swine, cattle and monkeys consume higher levels of fat per unit of diet than found in the prior art. In accordance therewith, it is highly desirable that pelleted feeds contain greater than 20 percent fat and upwards towards 50 percent fat in order that the feed provide the animals with an adequate supply of fat to fulfill its requisite energy needs while at the same time consuming lower levels of other feed ingredients. An additional advantage of high fat pellets is that of slicker more aesthetic coats rather than fulfilling the animals' appetites with other feed ingredients which are deficient in this regard. The present invention will provide a more efficient feed which can supply in a small portion of the diet, the fat needed by these animals.